Teaching safe prescribing to medical students: perspectives in the UK.

Prescribing is a characteristic role of a medical practitioner. On graduating from medical school, students are presumed to have acquired the necessary pharmacology knowledge underpinning the therapeutics and developed their personal skills and behaviors in order to write a safe and effective prescription (The Four Ps). However, there are reports of errors in medical prescribing and dissatisfied feedback from recent graduates, which evidence potential flaws in the current training in the practice of prescribing. We examine the Four Ps from a systems approach and offer scope for educators and curriculum designers to review and reflect on their current undergraduate teaching, learning, and assessment strategies in a similar manner. We also adopt a national framework of common competencies required of all prescribers to remain effective and safe in their area of practice as a more objective layer to the broader learning outcomes of the General Medical Council Tomorrow's Doctors 2009. This exercise demonstrates where standard, recognized competencies for safe prescribing can be accommodated pedagogically within existing medical curricula.

A study to investigate the effectiveness of SimMan® as an adjunct in teaching preclinical skills to medical students.

BACKGROUND: Following the GMC's report on Tomorrow's Doctors, greater emphasis has been placed on training in clinical skills, and the integration of clinical and basic sciences within the curriculum to promote the development of effective doctors. The use of simulation in the learning environment has the potential to support the development of clinical skills in preclinical medical students whilst in a 'safe' environment, but currently there is little evidence on its effectiveness. METHODS: Seventy nine year one medical students were divided into two groups. A pre-test was conducted by both groups, after which one group performed chest examination on their peers whilst the other group examined the SimMan® manikin. Both groups subsequently performed a mid-test and crossed over so that the group that conducted peer examination examined the manikin and vice-versa. Finally a post-test was conducted. The students were scored for formative feedback whilst performing examinations. Students completed a feedback questionnaire at the end of the session. Data were analysed using a one-way ANOVA, independent t-test and 2- proportion Z test. RESULTS: When the two groups were compared, there was no significant difference in their pre-test and post-test knowledge scores, whereas mid-test knowledge scores increased significantly (P < 0.001), with the group using SimMan® initially scoring higher. A significant increase in the test scores was seen in both groups after using SimMan® (P < 0.001). Students' confidence increased significantly in differentiating between normal and abnormal signs (P < 0.001). Students highly valued the use of the manikin in the session with 96% of students reporting that it enhanced their learning experience. CONCLUSIONS: The study demonstrated a significant improvement in the students' knowledge after examining the manikin and students also reported an increase in their confidence. Students' feedback was generally very positive and they perceived the incorporation of manikin-based examinations useful to prepare them for future patient contact. The use of simulation in this context supports an integrated learning approach when used as an adjunct to peer examination, and can benefit the acquisition of clinical skills in preclinical medical students.

Substance misuse teaching in undergraduate medical education.

BACKGROUND: Over 12,000 hospital admissions in the UK result from substance misuse, therefore issues surrounding this need to be addressed early on in a doctor's training to facilitate their interaction with this client group. Currently, undergraduate medical education includes teaching substance misuse issues, yet how this is formally integrated into the curriculum remains unclear. METHODS: Semi-structured interviews with 17 key members of staff responsible for the whole or part of the undergraduate medical curriculum were conducted to identify the methods used to teach substance misuse. Using a previously devised toolkit, 19 curriculum co-ordinators then mapped the actual teaching sessions that addressed substance misuse learning objectives. RESULTS: Substance misuse teaching was delivered primarily in psychiatry modules but learning objectives were also found in other areas such as primary care placements and problem-based learning. On average, 53 teaching sessions per medical school focused on bio-psycho-social models of addiction whereas only 23 sessions per medical school focused on professionalism, fitness to practice and students' own health in relation to substance misuse. Many sessions addressed specific learning objectives relating to the clinical features of substance dependence whereas few focused on iatrogenic addiction. CONCLUSIONS: Substance misuse teaching is now inter-disciplinary and the frequent focus on clinical, psychological and social effects of substance misuse emphasises the bio-psycho-social approach underlying clinical practice. Some areas however are not frequently taught in the formal curriculum and these need to be addressed in future changes to medical education.

Do students learn to be more conscientious at medical school?

BACKGROUND: Professionalism in medical students is not only difficult to define but difficult to teach and measure. As negative behaviour in medical students is associated with post-graduate disciplinary action it would be useful to have a model whereby unprofessional behaviour at the undergraduate level can easily be identified to permit appropriate intervention. We have previously developed a scalar measure of conscientiousness, the Conscientiousness Index (CI), which positively correlates to estimates of professional behaviour in undergraduate medical students. By comparing CI points awarded in year 1 and year 2 of study we were able to use the CI model to determine whether teaching and clinical exposure had any effect on students' conscientiousness. METHODS: CI points were collected by administrative staff from 3 successive cohorts of students in years 1 and 2 of study. Points were awarded to students for activities such as submission of immunisation status and criminal record checks, submission of summative assignments by a specified date and attendance at compulsory teaching sessions. CI points were then converted to a percentage of maximal possible scores (CI %) to permit direct comparison between years 1 and 2 of study. RESULTS: CI % scores were generally high with each year of study for each cohort showing negatively skewed normal distributions with peaks > 89%. There was a high degree of correlation of CI % scores between year 1 and year 2 of study for each cohort alone and when cohort data was combined. When the change in CI % from year 1 to year 2 for all students was compared there was no significant difference in conscientiousness observed. CONCLUSIONS: We have provided evidence that use of a CI model in undergraduate medical students provides a reliable measure of conscientiousness that is easy to implement. Importantly this study shows that measurement of conscientiousness by the CI model in medical students does not change between years 1 and 2 study suggesting that it is a stable characteristic and not modified by teaching and clinical exposure.

Modulation of gap-junction-dependent arterial relaxation by ascorbic acid.

AIMS: To investigate whether ascorbic acid (AA) can influence endothelium-dependent relaxation by modulating the spread of endothelial hyperpolarization through the arterial wall via gap junctions. METHODS: Force development and membrane potential were monitored by myography and sharp electrode techniques in isolated rabbit iliac arteries. RESULTS: AA prevented the ability of the gap junction blocker 2-aminoethoxydiphenyl borate to inhibit endothelium-dependent relaxations and subintimal smooth muscle hyperpolarizations evoked by cyclopiazonic acid in the presence of nitric oxide (NO) synthase and cyclooxygenase blockade. AA also prevented the ability of a connexin-mimetic peptide targeted against Cx37 and Cx40 (37,40Gap 26) to attenuate the transmission of endothelial hyperpolarization to subintimal smooth muscle, and a peptide targeted against Cx43 (43Gap 26) to attenuate the spread of subintimal hyperpolarization to subadventitial smooth muscle and the associated mechanical relaxation. Parallel studies with endothelium-denuded preparations demonstrated that AA and cyclopiazonic acid both depressed relaxation evoked by the NO donor MAHMA NONOate. CONCLUSIONS: The data suggest that AA can modulate arterial function through a previously unrecognized ability to preserve electrotonic signalling via myoendothelial and homocellular smooth muscle gap junctions under conditions where cell coupling is depressed. Underlying mechanisms do not involve amplification of 'residual' NO activity by AA.

5-Methyltetrahydrofolate and tetrahydrobiopterin can modulate electrotonically mediated endothelium-dependent vascular relaxation.

We have investigated the ability of 5-methyltetrahydrofolate (5-MTHF) and tetrahydrobiopterin (BH(4)) to modulate nitric oxide (NO)-independent vascular relaxations that are mediated by the sequential spread of endothelial hyperpolarization through the wall of the rabbit iliac artery by means of myoendothelial and homocellular smooth muscle gap junctions. Relaxations and subintimal smooth muscle hyperpolarizations evoked by cyclopiazonic acid were depressed by the gap junction inhibitor 2-aminoethoxydiphenyl borate, whose effects were prevented by 5-MTHF and BH(4), but not by their oxidized forms folic acid and 7,8-dihydrobiopterin. Analogously, 5-MTHF and BH(4), but not folic acid or 7,8-dihydrobiopterin, attenuated the depression of subintimal hyperpolarization by a connexin-mimetic peptide targeted against Cx37 and Cx40 ((37,40)Gap 26) and the depression of subadventitial hyperpolarization by a peptide targeted against Cx43 ((43)Gap 26), thus reflecting the known differential expression of Cx37 and Cx40 in the endothelium and Cx43 in the media of the rabbit iliac artery. The inhibitory effects of 2-aminoethoxydiphenyl borate and (37,40)Gap 26 against subintimal hyperpolarization were prevented by catalase, which destroys H(2)O(2). 5-MTHF and BH(4) thus appear capable of modulating electrotonic signaling by means of myoendothelial and smooth muscle gap junctions by reducing oxidant stress, potentially conferring an ability to reverse the endothelial dysfunction found in disease states through mechanisms that are independent of NO.

Connexin-mimetic peptides dissociate electrotonic EDHF-type signalling via myoendothelial and smooth muscle gap junctions in the rabbit iliac artery.

Synthetic peptides corresponding to the Gap 26 and Gap 27 domains of the first and second extracellular loops of the major vascular connexins (Cx37, Cx40 and Cx43), designated as (43)Gap 26, (40)Gap 27, (37,40)Gap 26 and (37,43)Gap 27 according to Cx homology, were used to investigate the role of gap junctions in the spread of endothelial hyperpolarizations evoked by cyclopiazonic acid (CPA) through the wall of the rabbit iliac artery. Immunostaining and confocal microscopy demonstrated that gap junction plaques constructed from Cx37 and Cx40 were abundant in the endothelium, whereas Cx43 was the dominant Cx visualized in the media. None of the Cx-mimetic peptides affected endothelial hyperpolarizations evoked by CPA directly. When administered individually, (40)Gap 27, (37,40)Gap 26 and (37,43)Gap 27, but not (43)Gap 26, attenuated endothelium-dependent subintimal smooth muscle hyperpolarization. By contrast, only (43)Gap 26 and (37,43)Gap 27 reduced the spread of subintimal hyperpolarization through the media of the rabbit iliac artery. The site of action of the peptides therefore correlated closely with the expression of their target Cxs in detectable gap junction plaques. The findings provide further evidence that the EDHF phenomenon is electrotonic in nature, and highlight the contribution of myoendothelial and homocellular smooth muscle communication via gap junctions to arterial function.

Enhanced inhibition of the EDHF phenomenon by a phenyl methoxyalaninyl phosphoramidate derivative of dideoxyadenosine.

In rabbit arteries endogenous production of cAMP facilitates electrotonic signalling via gap junctions, thus explaining the ability of P-site inhibitors of adenylyl cyclase to attenuate EDHF-type responses. In the present study, we show that a lipophilic phosphoramidate pronucleotide derivative of dideoxyadenosine, 2',3'-ddA-PMAPh, exhibits enhanced activity as an inhibitor of EDHF-type smooth muscle hyperpolarizations induced by acetylcholine (ACh) compared to the parent nucleoside 2',3'-ddA, and that the effects of both compounds can be reversed by the cAMP phosphodiesterase inhibitor IBMX. Neither 2',3'-ddA nor 2',3'-ddA-PMAPh depress ACh-evoked endothelial hyperpolarization directly. Modifications in the lipophilicity of dideoxyadenosine and its direct intracellular delivery as a mononucleotide may thus enhance the ability to inhibit adenylyl cyclase and depress electrotonic signalling via myoendothelial gap junctions.

The obligatory link: role of gap junctional communication in endothelium-dependent smooth muscle hyperpolarization.

Although an endothelium-derived hyperpolarizing factor (EDHF) has often been hypothesized to underpin vascular relaxations that are independent of nitric oxide (NO) and prostanoids, bioassay techniques have failed to confirm the existence of a freely transferable EDHF in a consistent fashion. Indeed, observations that inhibitors of direct cell-cell coupling such as connexin-mimetic peptides (e.g. Gap 26 and 27) and glycyrrhetinic acid derivatives attenuate "EDHF-type" smooth muscle hyperpolarizations and relaxations suggest that an electrotonic spread of endothelial hyperpolarization via myoendothelial and homocellular smooth muscle gap junctions plays an obligatory role in such responses. The endothelial hyperpolarization that initiates relaxation results from the opening of K(Ca) channels and is sustained by capacitative Ca(2+) entry triggered by the depletion of intracellular Ca(2+) stores in the endoplasmic reticulum. EDHF-type relaxations are also associated with a prostanoid-independent synthesis of cAMP that increases the conductance of gap junction channels and enhances the transmission of endothelial hyperpolarization through the vascular wall in a permissive fashion. This review will discuss the roles of these interacting signalling pathways in the mediation of the EDHF phenomenon.

Distinct hyperpolarizing and relaxant roles for gap junctions and endothelium-derived H2O2 in NO-independent relaxations of rabbit arteries.

We have compared the contributions of gap junctional communication and chemical signaling via H2O2 to NO-independent relaxations evoked by the Ca2+ ionophore A23187 and acetylcholine (ACh) in rabbit ilio-femoral arteries. Immunostaining confirmed the presence of connexins (Cxs) 37 and 40 in the endothelium and Cxs 40 and 43 in smooth muscle. Maximal endothelium-dependent subintimal smooth muscle hyperpolarizations evoked by A23187 and ACh were equivalent (approximately 20 mV) and almost abolished by an inhibitory peptide combination targeted against Cxs 37, 40, and 43. However, maximal NO-independent relaxations evoked by A23187 were unaffected by such peptides, whereas those evoked by ACh were depressed by approximately 70%. By contrast, the enzyme catalase, which destroys H2O2, attenuated A23187-induced relaxations over a broad range of concentrations, but only minimally depressed the maximum response to ACh. Catalase did not affect A23187- or ACh-evoked hyperpolarizations. After loading with an H2O2-sensitive probe, A23187 caused a marked increase in endothelial fluorescence that correlated temporally with relaxation, whereas only a weak delayed increase was observed with ACh. In arteries without endothelium, the H2O2-generating system xanthine/xanthine oxidase induced a catalase-sensitive relaxation that mimicked the gap junction-independent response to A23187 as it was maximally equivalent to approximately 80% of induced tone, but associated with a smooth muscle hyperpolarization <5 mV. We conclude that myoendothelial gap junctions underpin smooth muscle hyperpolarizations evoked by A23187 and ACh, but that A23187-induced relaxation is dominated by extracellular release of H2O2. Endothelium-derived H2O2 may thus be regarded as a relaxing factor, but not a hyperpolarizing factor, in rabbit arteries.

Essential role of Gap junctions in NO- and prostanoid-independent relaxations evoked by acetylcholine in rabbit intracerebral arteries.

BACKGROUND AND PURPOSE: Direct intercellular communication via gap junctions may play a central role in endothelium-dependent relaxations that are mediated by a conducted hyperpolarization and do not involve the synthesis of NO and prostanoids. In the present study, inhibitory peptides homologous to the Gap27 domain of the second extracellular loop of connexin37/connexin43 and connexin40, designated as 37,43Gap27 and 40Gap27, respectively, were used to evaluate the role of this mechanism in intracerebral arteries. METHODS: Isolated rings of rabbit middle cerebral artery were constricted by histamine (10 micromol/L) in the presence of N(G)-nitro-L-arginine methyl ester (300 micromol/L) and indomethacin (10 micromol/L). Concentration-relaxation curves for acetylcholine were constructed in the presence and absence of 37,43Gap27 and 40Gap27. Specific antibodies were used to delineate the distribution of connexin37, connexin40, connexin43, and connexin45 within the arterial wall. RESULTS: Individually, 37,43Gap27 and 40Gap27 minimally affected endothelium-dependent relaxations to acetylcholine at concentrations of 300 micro mol/L, whereas their combination (at 300 micromol/L each) inhibited the maximal response by approximately 70% and increased the EC50 value for relaxation by approximately 15-fold. In endothelium-denuded rings, this peptide combination did not attenuate responses to sodium nitroprusside, an exogenous source of NO. Gap junction plaques, whose incidence was highest in endothelium, were constructed from connexin40 and connexin43 in the media and connexin37, connexin40, and connexin43 in the endothelium. CONCLUSIONS: The findings confirm that direct communication via gap junctions contributes to agonist-induced relaxations of intracerebral arteries. More than one connexin subtype appears to participate in such responses.

cAMP facilitates EDHF-type relaxations in conduit arteries by enhancing electrotonic conduction via gap junctions.

We have investigated the role of cAMP in NO- and prostanoid-independent relaxations that are widely attributed to an endothelium-derived hyperpolarizing factor (EDHF). Under control conditions EDHF-type relaxations evoked by acetylcholine (ACh) in rabbit iliac arteries were transient, but in the presence of the cAMP phosphodiesterase inhibitor isobutylmethylxanthine (IBMX) or the cell permeant cAMP analog 8-bromo-cAMP, relaxations became sustained with their maxima potentiated approximately 2-fold. Relaxation was associated with transient approximately 1.5-fold elevations in smooth muscle cAMP levels with both mechanical and nucleotide responses being abolished by interrupting gap junctional communication with the connexin-mimetic peptide Gap 27 and by endothelial denudation. However, IBMX induced a sustained endothelium-independent approximately 2-fold rise in cAMP levels, which was not further amplified by ACh, suggesting that the contribution of cAMP to the EDHF phenomenon is permissive. After selective loading of the endothelium with calcein AM, direct transfer of dye from the endothelium to the media was enhanced by IBMX or 8-bromo-cAMP, but not by 8-bromo-cGMP, whereas Gap 27 promoted sequestration within the intima. ACh-induced hyperpolarizations of subintimal smooth muscle in arterial strips with intact endothelium were abolished by Gap 27 and the adenylyl cyclase inhibitor 2',5'-dideoxyadenosine but were unaffected by IBMX. By contrast, in strips partially denuded of endothelium, IBMX enhanced the transmission of hyperpolarization from the endothelium to remote smooth muscle cells. These findings support the hypothesis that endothelial hyperpolarization underpins the EDHF phenomenon, with cAMP governing subsequent electrotonic signaling via both myoendothelial and homocellular smooth muscle gap junctions.

Gap junction-dependent and -independent EDHF-type relaxations may involve smooth muscle cAMP accumulation.

We have compared the mechanisms that contribute to endothelium-derived hyperpolarizing factor (EDHF)-type responses induced by ACh and the Ca(2+) ionophore A-23187 in the rabbit iliac artery. Relaxations to both agents were associated with ~1.5-fold elevations in smooth muscle cAMP levels and were attenuated by the adenylyl cyclase inhibitor 2',5'-dideoxyadenosine (DDA) and potentiated by the cAMP phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Mechanical responses were inhibited by coadministration of the Ca(2+)-activated K(+) channel blockers apamin and charybdotoxin, both in the absence and presence of IBMX, but were unaffected by blockade of ATP-sensitive K(+) channels with the sulphonylurea glibenclamide. Relaxations and elevations in cAMP evoked by ACh were abolished by 18alpha-glycyrrhetinic acid, which disrupts gap junction plaques, whereas the corresponding responses to A-23187 were unaffected by this agent. Consistently, in "sandwich" bioassay experiments, A-23187, but not ACh, elicited extracellular release of a factor that evoked relaxations that were inhibited by DDA and potentiated by IBMX. These findings provide evidence that EDHF-type relaxations of rabbit iliac arteries evoked by ACh and A-23187 depend on cAMP accumulation in smooth muscle, but involve signaling via myoendothelial gap junctions and the extracellular space, respectively.